Calculating Loose Fill Insulation

cibula11

I am wanting to add some blown insulation to the knee wall space in my attic. I currently have 6 inches of loose fill on half and rock wool on the other half. I am wondering what R-value I need. I have read some things that say R49 in this space. If so, I would need to add R-37 or 11 inches of insulation? Is that correct or is adding too much going to cause problems?

FYI--I live in Iowa....current windchill -10.

jaw22

http://www.greenfiber.com/homeowners/how_to_one.asp This is a link to help you calculate which accounts for settling. Adding too much wont be a problem at all. Be sure that the actual kneewall itself has insulation behind it at least R19 and covered with taped housewrap or R13 fiberglass with sealed foamboard nailed to the studs and caulked/foamed to prevent air inflltration and windwash on the fiberglass on the wall.